Solder paste and printed circuit board

1. A solder paste comprising an alloy powder blended with a flux, wherein the alloy powder is a powder mixture consisting of a plurality of powders each of which is a Sn—Zn based alloy powder not containing Ag or a Sn—Ag based alloy not containing Zn, each of the plurality of powders is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Bi ternary alloy powder, a Sn—Zn—In ternary alloy powder, a Sn—Zn—Cu ternary alloy powder, a Sn—Zn—Sb ternary alloy powder, a Sn—Zn—Bi—In quaternary alloy powder, a Sn—Zn—Cu—Bi quaternary alloy powder, a Sn—Zn—Cu—In quaternary alloy powder, a Sn—Zn—Cu—Sb quaternary alloy powder, a Sn—Zn—Bi—Sb quaternary alloy powder, a Sn—Zn—In—Sb quaternary alloy powder, a Sn—Zn—Cu—Bi—In five-element alloy powder, a Sn—Zn—Cu—Bi—Sb five-element alloy powder, a Sn—Zn—Cu—In—Sb five-element alloy powder, a Sn—Zn—Bi—In—Sb five-element alloy powder, a Sn—Zn—Cu—Bi—In—Sb six-element alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—Cu ternary alloy powder, a Sn—Ag—In ternary alloy powder, a Sn—Ag—Sb ternary alloy powder, a Sn—Ag—Cu—Bi quaternary alloy powder, a Sn—Ag—Cu—In quaternary alloy powder, a Sn—Ag—Bi—In quaternary alloy powder, a Sn—Ag—Cu—Sb quaternary alloy powder, a Sn—Ag—Bi—Sb quaternary alloy powder, a Sn—Ag—In—Sb quaternary alloy powder, a Sn—Ag—Cu—Bi—In five-element alloy powder, a Sn—Ag—Cu—Bi—Sb five-element alloy powder, a Sn—Ag—Cu—In—Sb five-element alloy powder, a Sn—Ag—Bi—In—Sb five-element alloy powder, and a Sn—Ag—Cu—Bi—In—Sb six-element alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, one or more selected from the group consisting of 0.002-1.0 mass % of Cu, 0.005-15 mass % of Si, 0.005-15 mass % of In, and 0.005-1.0 mass % of Sb, and a remainder of Sn.

2. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Cu ternary alloy powder, a Sn—Ag binary alloy powder, and a Sn—Ag—Cu ternary alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.002-1.0 mass % of Cu, and a remainder of Sn.

3. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Bi ternary alloy powder, and a Sn—Ag binary alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.005-15 mass % of Bi, and a remainder of Sn.

4. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—In ternary alloy powder, a Sn—Ag binary alloy powder, and a Sn—Ag—In ternary alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.005-15 mass % of In, and a remainder of Sn.

5. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Bi ternary alloy powder, a Sn—Zn—Cu ternary alloy powder, a Sn—Zn—Cu—Bi quaternary alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—Cu ternary alloy powder, and a Sn—Ag—Cu—Bi quaternary alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.002-1.0 mass % of Cu, 0.005-15 mass % of Bi, and a remainder of Sn.

6. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—In ternary alloy powder, a Sn—Zn—Cu ternary alloy powder, a Sn—Zn—Cu—In quaternary alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—Cu ternary alloy powder, a Sn—Ag—In ternary alloy powder, and a Sn—Ag—Cu—In quaternary alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.002-1.0 mass % of Cu, 0.005-15 mass % of In, and a remainder of Sn.

7. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Bi ternary alloy powder, a Sn—Zn—In ternary alloy powder, a Sn—Zn—Bi—In quaternary alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—In ternary alloy powder, and a Sn—Ag—Bi—In quaternary alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.005-15 mass % of Bi, 0.005 is mass % of In, and a remainder of Sn.

8. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Bi ternary alloy powder, a Sn—Zn—In ternary alloy powder, a Sn—Zn—Cu ternary alloy powder, a Sn—Zn—Cu—Bi quaternary alloy powder, a Sn—Zn—Cu—In quaternary alloy powder, a Sn—Zn—Bi—In quaternary alloy powder, a Sn—Zn—Cu—Bi—In five-element alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—Cu ternary alloy powder, a Sn—Ag—In ternary alloy powder, a Sn—Ag—Cu—Bi quaternary alloy powder, a Sn—Ag—Cu—In quaternary alloy powder, a Sn—Ag—Bi—In quaternary alloy powder, and a Sn—Ag—Cu—Bi—In five-element alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.002-1.0 mass % of Cu, 0.005-15 mass % of Bi, 0.005-15 mass % of In, and a remainder of Sn.

9. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Sb ternary alloy powder, a Sn—Ag binary alloy powder, and a Sn—Ag—Sb ternary alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.005-1.0 mass percent of Sb, and a remainder of Sn.

10. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Cu ternary alloy powder, a Sn—Zn—Sb ternary alloy powder, a Sn—Zn—Cu—Sb quaternary alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—Cu ternary alloy powder, a Sn—Ag—Sb ternary alloy powder, and a Sn—Ag—Cu—Sb quaternary alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.002-1.0 mass % of Cu, 0.005-1.0 mass % of Sb, and a remainder of Sn.

11. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Bi ternary alloy powder, a Sn—Zn—Sb ternary alloy powder, a Sn—Zn—Bi—Sb quaternary alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—Sb ternary alloy powder, and a Sn—Ag—Bi—Sb quaternary alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0005-15 mass % of Ag, 0.005-15 mass % of Bi, 0.005-1.0 mass % of Sb, and a remainder of Sn.

12. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—In ternary alloy powder, a Sn—Zn—Sb ternary alloy powder, a Sn—Zn—In—Sb quaternary alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—In ternary alloy powder, a Sn—Ag—Sb ternary alloy powder, and a Sn—Ag—In—Sb quaternary alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.005-15 mass % of In, 0005-1.0 mass % of Sb, and a remainder of Sn.

13. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Bi ternary alloy powder, a Sn—Zn—Cu ternary alloy powder, a Sn—Zn—Sb ternary alloy powder, a Sn—Zn—Cu—Bi quaternary alloy powder, a Sn—Zn—Cu—Sb quaternary alloy powder, a Sn—Zn—Bi—Sb quaternary alloy powder, a Sn—Zn—Cu—Bi—Sb five-element alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—Cu ternary alloy powder, a Sn—Ag—Sb ternary alloy powder, a Sn—Ag—Cu—Bi quaternary alloy powder, a Sn—Ag—Cu—Sb quaternary alloy powder, a Sn—Ag—Bi—Sb quaternary alloy powder, and a Sn—Ag—Cu—Bi—Sb five-element alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.002-1.0 mass % of Cu, 0.005-15 mass % of Bi, 0.005-1.0 mass % of Sb, and a remainder of Sn.

14. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—In ternary alloy powder, a Sn—Zn—Cu ternary alloy powder, a Sn—Zn—Sb ternary alloy powder, a Sn—Zn—Cu—In quaternary alloy powder, a Sn—Zn—Cu—Sb quaternary alloy powder, a Sn—Zn—In—Sb quaternary alloy powder, a Sn—Zn—Cu—In—Sb five-element alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—Cu ternary alloy powder, a Sn—Ag—In ternary alloy powder, a Sn—Ag—Sb ternary alloy powder, a Sn—Ag—Cu—In quaternary alloy powder, a Sn—Ag—Cu—Sb quaternary alloy powder, a Sn—Ag—In—Sb quaternary alloy powder, and a Sn—Ag—Cu—In—Sb five-element alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.002-1.0 mass % of Cu, 0.005-15 mass % of In, 0.005-1.0 mass % of Sb, and a remainder of Sn.

15. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Bi ternary alloy powder, a Sn—Zn—In ternary alloy powder, a Sn—Zn—Sb ternary alloy powder, a Sn—Zn—Bi—In quaternary alloy powder, a Sn—Zn—Bi—Sb quaternary alloy powder, a Sn—Zn—In—Sb quaternary alloy powdery a Sn—Zn—Bi—In—Sb five-element alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—In ternary alloy powder, a Sn—Ag—Sb ternary alloy powder, Sn—Ag—Bi—In quaternary alloy powder, a Sn—Ag—Bi—Sb quaternary alloy powder, a Sn—Ag—In—Sb quaternary alloy powder, and a Sn—Ag—Bi—In—Sb five-element alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.005-15 mass % of Bi, 0.005-15 mass % of In, 0.005-1.0 mass % of Sb, and a remainder of Sn.

16. A solder paste as claimed in claim 1 wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Bi ternary alloy powder, a Sn—Zn—In ternary alloy powder, a Sn—Zn—Cu ternary alloy powder, a Sn—Zn—Sb ternary alloy powder, a Sn—Zn—Bi—In quaternary alloy powder, a Sn—Zn—Cu—Bi quaternary alloy powder, a Sn—Zn—Cu—In quaternary alloy powder, a Sn—Zn—Cu—Sb quaternary alloy powder, a Sn—Zn—Bi—Sb quaternary alloy powder, a Sn—Zn—In—Sb quaternary alloy powder, a Sn—Zn—Cu—Bi—In five-element alloy powder, a Sn—Zn—Cu—Bi—Sb five-element alloy powder, a Sn—Zn—Cu—In—Sb five-element alloy powder, a Sn—Zn—Bi—In—Sb five-element alloy powder, a Sn—Zn—Cu—Bi—In—Sb six-element allay powder, a Sn—Ag binary alloy powder, a Sn—Ag—Cu ternary alloy powder, a Sn—Ag—In ternary alloy powder, a Sn—Ag—Sb ternary alloy powder, a Sn—Ag—Cu—Bi quaternary alloy powder, a Sn—Ag—Cu—In quaternary alloy powder, a Sn—Ag—Bi—In quaternary alloy powder, a Sn—Ag—Cu—Sb quaternary alloy powder, a Sn—Ag—Bi—Sb quaternary alloy powder, a Sn—Ag—In—Sb quaternary alloy powder, a Sn—Ag—Cu—Bi—In five-element alloy powder, a Sn—Ag—Cu—Bi—Sb five-element alloy powder, a Sn—Ag—Cu—In—Sb five-element alloy powder, a Sn—Ag—Bi—In—Sb five-element alloy powder, and a Sn—Ag—Cu—Bi—In—Sb six-element alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-15 mass % of Ag, 0.002-1.0 mass % of Cu, 0.005-15 mass % of Si, 0.005-15 mass % of In, 0005-1.0 mass % of Sb, and a remainder of Sn.

17. A solder paste as claimed in claim 1 , wherein each powder in the powder mixture is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Bi ternary alloy powder, a Sn—Zn—In ternary alloy powder, a Sn—Zn—Cu ternary alloy powder, a Sn—Zn—Bi—In quaternary alloy powder, a Sn—Zn—Cu—Bi quaternary alloy powder, a Sn—Zn—Cu—In quaternary alloy powder, a Sn—Zn—Cu—Bi—In five-element alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—Cu ternary alloy powder, a Sn—Ag—In ternary alloy powder, a Sn—Ag—Cu—Bi quaternary alloy powder, a Sn—Ag—Cu—In quaternary alloy powder, a Sn—Ag—Bi—In quaternary alloy powder, and a Sn—Ag—Cu—Bi—In five-element alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, one or more selected from the group consisting of 0.002-1.0 mass % of Cu, 0.005-15 mass % of Bi, and 0.005-15 mass % of In, and a remainder of Sn.

18. A solder paste as claimed in claim 17 wherein the amount in the powder mixture of a Sn—Ag binary alloy powder and a Sn—Ag based alloy powder comprising Sn, Ag, and at least one additional element is at most 30 mass % of the powder mixture.

19. A solder paste comprising an alloy powder blended with a flux, wherein the alloy powder is a powder mixture consisting of a plurality of powders each of which is a Sn—Zn based alloy powder not containing Ag or a Sn—Ag based alloy powder not containing Zn, each of the plurality of powders is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Bi ternary alloy powder, a Sn—Zn—In ternary alloy powder, a Sn—Zn—Cu ternary alloy powder, a Sn—Zn—Sb ternary alloy powder, a Sn—Zn—Bi—In quaternary alloy powder, a Sn—Zn—Cu—Bi quaternary alloy powder, a Sn—Zn—Cu—In quaternary alloy powder, a Sn—Zn—Cu—Sb quaternary alloy powder, a Sn—Zn—Bi—Sb quaternary alloy powder, a Sn—Zn—In—Sb quaternary alloy powder, a Sn—Zn—Cu—Bi—in five-element alloy powder, a Sn—Zn—Cu—Bi—Sb five-element alloy powder, a Sn—Zn—Cu—In—Sb five-element alloy powder, a Sn—Zn—Bi—In—Sb five-element alloy powder, a Sn—Zn—Cu—Bi—In—Sb six-element alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—Cu ternary alloy powder, a Sn—Ag—Bi ternary alloy powder, a Sn—Ag—In ternary alloy powder, a Sn—Ag—Sb ternary alloy powder, a Sn—Ag—Cu—Bi quaternary alloy powder, a Sn—Ag—Cu—In quaternary alloy powder, a Sn—Ag—Bi—In quaternary alloy powder, a Sn—Ag—Cu—Sb quaternary alloy powder, a Sn—Ag—Bi—Sb quaternary alloy powder, a Sn—Ag—In—Sb quaternary alloy powder, a Sn—Ag—Cu—Bi—In five-element alloy powder, a Sn—Ag—Cu—Bi—Sb five-element alloy powder, a Sn—Ag—Cu—In—Sb five-element alloy powder, a Sn—Ag—Bi—In—Sb five-element alloy powder, and a Sn—Ag—Cu—Bi—In—Sb six-element alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, 0.005-1.0 mass % of Sb, from zero to three elements selected from the group consisting of 0.002-1.0 mass % of Cu, 0.005-15 mass % of Bi, and 0.005-15 mass % of In, and a remainder of Sn.